Some compilers don't have -Wvla.

Index: lib/libzstd.mk
--- lib/libzstd.mk.orig
+++ lib/libzstd.mk
@@ -100,7 +100,7 @@ endif
 DEBUGFLAGS= -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow \
             -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement \
             -Wstrict-prototypes -Wundef -Wpointer-arith \
-            -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings \
+            -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings \
             -Wredundant-decls -Wmissing-prototypes -Wc++-compat
 CFLAGS   += $(DEBUGFLAGS) $(MOREFLAGS)
 ASFLAGS  += $(DEBUGFLAGS) $(MOREFLAGS) $(CFLAGS)
@@ -197,6 +197,8 @@ else ifeq ($(UNAME), FreeBSD)
 else ifeq ($(UNAME), NetBSD)
   HASH ?= md5 -n
 else ifeq ($(UNAME), OpenBSD)
+  HASH ?= md5
+else ifeq ($(UNAME), SecBSD)
   HASH ?= md5
 endif
 HASH ?= md5sum